Incidence of cardiovascular events in polymyalgia rheumatica and giant cell arteritis amongst an Asian population: Propensity score matched cohort study

Background: The hypothesis that patients with polymyalgia rheumatica (PMR) or giant cell arteritis (GCA) have a high risk for future cardiovascular diseases has not been adequately tested. The aim of this study is to evaluate this hypothesis in Japan, where the prevalence and severity of PMR and GCA are the lowest. Methods: A propensity score matched cohort study was conducted at St. Luke's International Hospital, Tokyo, Japan, from 2003 to 2016. We included all patients who were diagnosed as PMR or GCA cases and matched comparators with a proportion of 1 : 2. Our primary outcome was newly diagnosed cardiovascular disease. The propensity score was calculated using logistic regression with forward stepwise selection in 30 variables. Kaplan–Meier curves were drawn and the log-rank test and Cox proportional hazard model were performed for survival analyses. Two types of sensitivity analyses were conducted to confirm the results. Results: Among 2461 potential patients, the propensity score identified 504 (168 cases and 336 comparators) patients. During follow up (median 839.5 days), 110 (21.8%) developed cardiovascular diseases. The Kaplan–Meier curves between those with and without PMR or GCA were not significantly different (P = 0.85). The Cox proportional hazard model calculated the hazard ratio (HR) of those with PMR or GCA compared to those without as 0.96 (95% CI: 0.64–1.46). The results from sensitivity analyses were consistent (HR 0.70–1.06). Conclusion: Patients with PMR or GCA may not have a higher risk of future cardiovascular diseases among the Japanese population. The sensitivity analyses and sample size calculation supported the results.